Question

我有八个表，其中包含有关整个公司对应用程序进行的更改的信息。我只想查询和合并200多个应用程序的子集的行。为此，我要通过应用程序代码（AAA，BBB等）查询每个表，并希望合并结果。当我使用超过5个应用程序代码时，出现错误“查询复杂”。

我知道有一种更有效的方法可以做到这一点，但是以下是我在有限的知识基础上能够做到的最好的方法。

SELECT * FROM [2019-07-A July 5 to 7]   WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-07-B July 12 to 14] WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-07-C July 19 to 21] WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-07-D July 26 to 28] WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-08-A Aug 2 to 4]    WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-08-B Aug 9 to 11]   WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-08-C Aug 16 to 18]  WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-08-D Aug 23 to 25 Proposed] WHERE [Application code] LIKE 'AAA' UNION ALL 
SELECT * FROM [2019-07-A July 5 to 7]   WHERE [Application code] LIKE 'BBB' UNION ALL 
SELECT * FROM [2019-07-B July 12 to 14] WHERE [Application code] LIKE 'BBB' UNION ALL 
SELECT * FROM [2019-07-C July 19 to 21] WHERE [Application code] LIKE 'BBB' UNION ALL 
SELECT * FROM [2019-07-D July 26 to 28] WHERE [Application code] LIKE 'BBB' UNION ALL 
SELECT * FROM [2019-08-A Aug 2 to 4]    WHERE [Application code] LIKE 'BBB' UNION ALL 
SELECT * FROM [2019-08-B Aug 9 to 11]   WHERE [Application code] LIKE 'BBB' UNION ALL 
SELECT * FROM [2019-08-C Aug 16 to 18]  WHERE [Application code] LIKE 'BBB' UNION ALL
SELECT * FROM [2019-08-D Aug 23 to 25 Proposed] WHERE [Application code] LIKE 'BBB';

我希望能够一次查询所有200多个应用程序代码，并且比每个代码键入相同的字符串8次更有效。

Answer 1

一种更简单的方法可能是在应用选择标准之前在{em> 之前union表数据，这样您只需在一个位置指定条件，例如：

select * from
(
    select * from [2019-07-A July 5 to 7]   union all 
    select * from [2019-07-B July 12 to 14] union all 
    select * from [2019-07-C July 19 to 21] union all 
    select * from [2019-07-D July 26 to 28] union all 
    select * from [2019-08-A Aug 2 to 4]    union all 
    select * from [2019-08-B Aug 9 to 11]   union all 
    select * from [2019-08-C Aug 16 to 18]  union all 
    select * from [2019-08-D Aug 23 to 25 Proposed]
) as t
where
    t.[Application code] like 'AAA' or
    t.[Application code] like 'BBB'

如果您在like语句的条件内不使用通配符，则可以选择使用in运算符并提供应用程序代码列表：< / p>

select * from
(
    select * from [2019-07-A July 5 to 7]   union all 
    select * from [2019-07-B July 12 to 14] union all 
    select * from [2019-07-C July 19 to 21] union all 
    select * from [2019-07-D July 26 to 28] union all 
    select * from [2019-08-A Aug 2 to 4]    union all 
    select * from [2019-08-B Aug 9 to 11]   union all 
    select * from [2019-08-C Aug 16 to 18]  union all 
    select * from [2019-08-D Aug 23 to 25 Proposed]
) as t
where
    t.[Application code] in ('AAA', 'BBB')

或者，您可以创建一个包含所有要返回的应用程序代码的表（在下面的示例中，我已经将这样的表ApplicationCodes称为包含单个字段Code的表），并且然后使用简单的联接隐式应用过滤，例如：

select * from
(
    select * from [2019-07-A July 5 to 7]   union all 
    select * from [2019-07-B July 12 to 14] union all 
    select * from [2019-07-C July 19 to 21] union all 
    select * from [2019-07-D July 26 to 28] union all 
    select * from [2019-08-A Aug 2 to 4]    union all 
    select * from [2019-08-B Aug 9 to 11]   union all 
    select * from [2019-08-C Aug 16 to 18]  union all 
    select * from [2019-08-D Aug 23 to 25 Proposed]
) as t 
inner join ApplicationCodes on t.[Application code] = ApplicationCodes.Code

Answer 2

我建议您创建一个包含所有应用程序的表，然后仅执行8个查询

SELECT * FROM [2019-07-A July 5 to 7] f, [Applications]  a 
 WHERE f.[Application code] = a.[Application code] UNION ALL
SELECT * FROM [2019-07-B July 12 to 14] f, [Applications]  a 
 WHERE f.[Application code] = a.[Application code] UNION ALL
etc...

如果您不喜欢这样做，可以尝试使用IN子句

SELECT * FROM [2019-07-A July 5 to 7]   WHERE [Application code] IN 
( 'AAA','BBB','CCC','DDD', etc...) UNION ALL 
SELECT * FROM [2019-07-B July 12 to 14] WHERE [Application code] IN 
( 'AAA','BBB','CCC','DDD', etc...) UNION ALL ALL

Answer 3

包含日期或序列号且具有相同字段的表名通常应与表名结合使用，以作为额外的功能。

使用已合并的表的字段创建表（例如ApplicationChanges），并添加一个将包含旧表名称的附加字段ChangedAt。也许旧表包含一个显示日期ChangedAt的日期字段，那么您可以省略表名并查询哪些日期属于该表。

然后使用@LeeMacs查询填充新表：

INSERT INTO ApplicationChanges
FROM
    (
        SELECT
            [2019-07-A July 5 to 7].*
          , '[2019-07-A July 5 to 7]' AS ChangedAt
        FROM
            [2019-07-A July 5 to 7]

        UNION ALL

        SELECT
            [2019-07-B July 12 to 14].*
          , '[2019-07-B July 12 to 14]' AS ChangedAt
        FROM
            [2019-07-B July 12 to 14]

        UNION ALL

        SELECT
            [2019-07-C July 19 to 21].*
          , '[2019-07-C July 19 to 21]' AS ChangedAt
        FROM
            [2019-07-C July 19 to 21]

        UNION ALL

        SELECT
            [2019-07-D July 26 to 28]*
          , '[2019-07-D July 26 to 28]' AS ChangedAt
        FROM
            [2019-07-D July 26 to 28]

        UNION ALL

        SELECT
            [2019-08-A Aug 2 to 4].*
          , '[2019-08-A Aug 2 to 4]' AS ChangedAt
        FROM
            [2019-08-A Aug 2 to 4]

        UNION ALL

        SELECT
            [2019-08-B Aug 9 to 11].*
          , '[2019-08-B Aug 9 to 11]' AS ChangedAt
        FROM
            [2019-08-B Aug 9 to 11]

        UNION ALL

        SELECT
            [2019-08-C Aug 16 to 18].*
          , '[2019-08-C Aug 16 to 18]' AS ChangedAt
        FROM
            [2019-08-C Aug 16 to 18]

        UNION ALL

        SELECT
            [2019-08-D Aug 23 to 25 Proposed].*
          , '[2019-08-D Aug 23 to 25 Proposed]' AS ChangedAt
        FROM
            [2019-08-D Aug 23 to 25 Proposed]
    )
    AS t

如果需要旧的数据结构，请使用ChangedAt作为条件为每个以前的表创建查询。例如。表[2019-07-A July 5 to 7]

SELECT *
FROM
    ApplicationChanges
WHERE
    ChangedAt = '[2019-07-A July 5 to 7]'
    AND [Application code] IN ('AAA'
                             , 'BBB');

不再需要缓慢的联合查询，

Microsoft Access联合查询导致“查询太复杂”错误

3 个答案: